Propfan propulsion systems for aircraft, also known variously as unducted fan and ultra-high bypass ratio systems, typically include a turboshaft gas turbine engine driving one or more rotors to which are attached a plurality of relatively thin, relatively highly curved propfan blades. As compared to conventional propeller systems, propfan systems achieve comparable or better propulsive efficiencies at aircraft mach numbers below .85. As compared to modern turbofan propulsion systems, propfan systems achieve greater propulsive efficiencies at comparable aircraft mach numbers. For tube-launched expendable vehicles, where aircraft range is a primary consideration, propfan propulsion represents a potentially attractive alternative to currently used turbofan propulsion. For such a system to be practical, however, the propfan blades must be attached to the rotor hubs through connections which permit flat storage of the blades prior to launch and rapid, automatic, and dependable deployment to permanently extended positions immediately after launch. A propfan blade-to-hub connection according to this invention responds to these requirements.